The use of membranes to effect separation of gas/gas, liquid/liquid, and liquid/solid mixtures and solutions has achieved general industrial applicability by various methods, among them being ultrafiltration, hyperfiltration, reverse osmosis, dialysis. In general, membrane elements associated with these processes are contained in vessels, comprising a container having various inlet and outlet ports and an assembly of membranes within said container, the entire assembly being referred to as a module. The internal configurations are so arranged as to permit the introduction of a feed stream with or without pressure on the upstream face of the membranes, means for collecting permeate which passes through the membranes and emerges on their downstream faces, and means for keeping feed and permeate materials from comingling.
Membranes have been fabricated in various shapes, such as (1) flat sheets which may be supported in a typical plate and frame structure similar to a filter press; (2) flat sheets rolled into spirals with spacing materials interleaved with the membrane and the assembly sealed to provide spiroidal channels permitting the passage of a feed on one side of the coiled membrane through spaces to the opposite side of the membrane; (3) as tubes lining the inner surface of a reinforced braid, the braid itself at times being a component in a larger tube; and (4) in the form of open-ended hollow fibers so organized and sealed into header plates as to provide a separation of the flows over the external surfaces of the hollow fibers from any flow within the bores of the hollow fibers ensuing by virtue of a passage of permeate across the membrane.
Of particular interest is the use of hollow fibers assembled in bundle form to provide the desired separation
In U.S. applications for Letters Patent Ser. Nos. 943,738 filed Sept. 19, 1978, 943,739 filed Sept. 19, 1978, 943,793 filed Sept. 19, 1978 and 956,032 filed Oct. 30, 1978, various techniques for the selection and winding of hollow fibers and the fabrication and assembly of such fibers into modular form is taught. It is noted however that for the practical usage of such modules in commercial application, small bundles in single bundle housings are too small. On the other hand as taught in the above noted applications other limitations exist which restrict the size of individual bundles.